Projection apparatus, projection method and computer-readable storage medium for correcting a projection state being projected onto curved surface

ABSTRACT

A chart generation unit generates an adjustment chart, and a projection unit projects the adjustment chart onto a circular cylinder. A parameter acquiring unit acquires 12 parameters in total, relating to the positions of four corners and middle points of a top side and a bottom side of a chart and lateral expansion of the chart, the chart being input by a user through manipulations of an operation unit. A transform function determination unit calculates, from the total of 12 parameters, an accurate transform function for projecting an image onto the circular cylinder. An image conversion unit applies geometric transformation to the image based on the calculated transform function.

BACKGROUND

1. Technical Field

The present invention relates to a projection apparatus, a projectionstate adjustment method, and a projection state adjustment program.

2. Related Art

Generally, a projector as an image projection apparatus is known, inwhich an image based on image data output from a personal computer, forexample, is projected onto a projection target such as a screen.

Such a projector is sometimes used to project an image onto the curvedsurface of a circular cylinder, for example.

For example, in the case where an image with no distortion isappropriately projected onto a circular cylinder, it is necessary toapply geometric correction to a projected image.

Functions for use in such geometric correction are different dependingon the positional relationship between the projector and the circularcylinder, such as the orientation of the projector relative to thecircular cylinder, a distance from the projector to the circularcylinder, and the diameter of the circular cylinder.

Thus, it is necessary to provide the settings of geometric correctiondepending on the positional relationship between the projector and thecircular cylinder, for example.

Some methods are known as a setting method for such geometriccorrection.

For example, a first method is a method in which a projector is used toproject a grid pattern onto a circular cylinder, and a user adjusts thepositions of intersection points of grids to sequentially change the setvalues of geometric correction.

A second method is a method in which a distance and a direction from aprojector to a circular cylinder, the range of a screen on the circularcylinder, the angle of view of the projector, the position of an opticalaxis, and so on are found, and correction values necessary for geometriccorrection are calculated from the values.

For a third method, a technique is disclosed in JP-A-2004-320662, forexample, in which typical geometric correction methods not directlyinvolved in a circular cylinder are combined to adjust images.

As for the foregoing setting methods for geometric correction, accordingto the first method, for example, the user can intuitively performmanipulations.

However, it is necessary to adjust a large number of positions ofintersection points, and it takes a lot of time and effort.

For example, in the second method, it is necessary to accuratelydetermine the positional relationship between the projector and thecircular cylinder, for example, which is usually difficult to determine,and it is difficult to implement the second method.

For example, according to the third method, the user can relativelyeasily perform manipulations because the amount of manipulations issmall.

However, it is difficult for the user to intuitively grasp whichgeometric correction methods to combine.

Moreover, the first method and the third method provide approximatesettings, and the methods do not always provide mathematically accuratecorrection.

SUMMARY

Therefore, it is an object of the present invention to provide aprojection apparatus, a projection state adjustment method, and aprojection state adjustment program that can accurately adjust theprojection of an image onto a circular cylinder surface with easymanipulations by intuition.

In order to achieve the above object, a projection apparatus accordingto an aspect of the present invention includes:

a projection unit configured to project an image onto a target area on acurved surface formed of generatrices of a circular cylinder;

an image conversion unit configured to apply geometric transformation toa projected image projected by the projection unit;

a parameter acquiring unit configured to acquire a parameter expressinga positional relationship between the projection unit and the curvedsurface; and

a transform function determination unit configured to determine atransform function for use in the geometric transformation based on theparameter,

wherein the target area is an area surrounded by:

-   -   a first line and a second line which are parallel to an axis of        the circular cylinder;    -   a third line that is an intersection line of a first plane        perpendicular to the axis with the curved surface; and    -   a fourth line that is an intersection line of a second plane        parallel to the first plane with the curved surface, and

when an image area is such an area that the image applied the geometrictransformation is projected onto the curved surface, the parameterincludes:

-   -   a four-corner parameter to match four corners of the image area        and four corners of the target area;    -   a first middle point parameter to match a first middle point        that is a middle point of a top side of the image area and a        middle point of the third line of the target area;    -   a second middle point parameter to match a second middle point        that is a middle point of a bottom side of the image area and a        middle point of the fourth line of the target area; and    -   a second reference line parameter to, when a line connecting the        first middle point to the second middle point of the image area        is a first reference line, adjust a position of a second        reference line provided between a left side of the image area        and the first reference line, or between a right side of the        image area and the first reference line.

In order to achieve the above object, a projection apparatus accordingto an aspect of the present invention includes:

a projection unit configured to project an image onto a target area on acurved surface formed of generatrices of a circular cylinder;

an image conversion unit configured to apply geometric transformation toa projected image projected by the projection unit;

a parameter acquiring unit configured to acquire a parameter expressinga positional relationship between the projection unit and the curvedsurface; and

a transform function determination unit configured to determine atransform function for use in the geometric transformation based on theparameter,

wherein the target area is an area surrounded by:

-   -   a first line and a second line which are parallel to an axis of        the circular cylinder;    -   a third line that is an intersection line of a first plane        perpendicular to the axis with the curved surface; and    -   a fourth line that is an intersection line of a second plane        parallel to the first plane with the curved surface, and

the geometric transformation includes:

-   -   rotation projection transformation between a plane and a plane;        and    -   circular cylinder geometric transformation between the target        area and a plane parallel to a third plane passing between the        first line and the second line.

In order to achieve the above object, a projection state adjustmentmethod according to an aspect of the present invention includes thesteps of:

projecting an image onto a target area on a curved surface formed ofgeneratrices of a circular cylinder from a projection unit;

applying geometric transformation to a projected image projected fromthe projection unit;

acquiring a parameter expressing a positional relationship between theprojection unit and the curved surface; and

determining a transform function for use in the geometric transformationbased on the parameter,

wherein the target area is an area surrounded by:

-   -   a first line and a second line which are parallel to an axis of        the circular cylinder;    -   a third line that is an intersection line of a first plane        perpendicular to the axis with the curved surface; and    -   a fourth line that is an intersection line of a second plane        parallel to the first plane with the curved surface, and

when an image area is such an area that the image applied the geometrictransformation is projected onto the curved surface, the parameterincludes:

-   -   a four-corner parameter to match four corners of the image area        and four corners of the target area;    -   a first middle point parameter to match a first middle point        that is a middle point of a top side of the image area and a        middle point of the third line of the target area;    -   a second middle point parameter to match a second middle point        that is a middle point of a bottom side of the image area and a        middle point of the fourth line of the target area; and    -   a second reference line parameter to, when a line connecting the        first middle point to the second middle point of the image area        is a first reference line, adjust a position of a second        reference line provided between a left side of the image area        and the first reference line, or between a right side of the        image area and the first reference line.

In order to achieve the above object, a projection state adjustmentmethod according to an aspect of the present invention includes thesteps of:

projecting an image onto a target area on a curved surface formed ofgeneratrices of a circular cylinder from a projection unit;

applying geometric transformation to a projected image projected fromthe projection unit;

acquiring a parameter expressing a positional relationship between theprojection unit and the curved surface; and

determining a transform function for use in the geometric transformationbased on the parameter,

wherein the target area is an area surrounded by:

-   -   a first line and a second line which are parallel to an axis of        the circular cylinder;    -   a third line that is an intersection line of a first plane        perpendicular to the axis with the curved surface; and    -   a fourth line that is an intersection line of a second plane        parallel to the first plane with the curved surface, and

the geometric transformation includes:

-   -   rotation projection transformation between a plane and a plane;        and    -   circular cylinder geometric transformation between the target        area and a plane parallel to a third plane passing between the        first line and the second line.

In order to achieve the above object, a non-transitory computer-readablestorage medium according to an aspect of the present invention stores aprojection state adjustment program that causes a computer to:

project an image onto a target area on a curved surface formed ofgeneratrices of a circular cylinder from a projection unit;

apply geometric transformation to a projected image projected from theprojection unit;

acquire a parameter expressing a positional relationship between theprojection unit and the curved surface; and

determine a transform function for use in the geometric transformationbased on the parameter,

wherein the target area is an area surrounded by:

-   -   a first line and a second line which are parallel to an axis of        the circular cylinder;    -   a third line that is an intersection line of a first plane        perpendicular to the axis with the curved surface; and    -   a fourth line that is an intersection line of a second plane        parallel to the first plane with the curved surface, and

when an image area such an area that the image applied the geometrictransformation is projected onto the curved surface, the parameterincludes:

-   -   a four-corner parameter to match four corners of the image area        and four corners of the target area;    -   a first middle point parameter to match a first middle point        that is a middle point of a top side of the image area and a        middle point of the third line of the target area;    -   a second middle point parameter to match a second middle point        that is a middle point of a bottom side of the image area and a        middle point of the fourth line of the target area; and    -   a second reference line parameter to, when a line connecting the        first middle point to the second middle point of the image area        is a first reference line, adjust a position of a second        reference line provided between a left side of the image area        and the first reference line, or between a right side of the        image area and the first reference line.

In order to achieve the above object, a non-transitory computer-readablestorage medium according to an aspect of the present invention stores aprojection state adjustment program that causes a computer to:

project an image onto a target area on a curved surface formed ofgeneratrices of a circular cylinder from a projection unit;

apply geometric transformation to a projected image projected from theprojection unit;

acquire a parameter expressing a positional relationship between theprojection unit and the curved surface; and

determine a transform function for use in the geometric transformationbased on the parameter,

wherein the target area is an area surrounded by:

-   -   a first line and a second line which are parallel to an axis of        the circular cylinder;    -   a third line that is an intersection line of a first plane        perpendicular to the axis with the curved surface; and    -   a fourth line that is an intersection line of a second plane        parallel to the first plane with the curved surface, and

the geometric transformation includes:

-   -   rotation projection transformation between a plane and a plane;        and    -   circular cylinder geometric transformation between the target        area and a plane parallel to a third plane passing between the        first line and the second line.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an exemplary configuration of a projectoraccording to an embodiment of the present invention;

FIG. 2 is a diagram illustrating projection of an image onto a circularcylinder using a projector;

FIG. 3 is a diagram illustrating the degree of freedom of the positionalrelationship between the projector and the circular cylinder;

FIG. 4 is a diagram illustrating the degree of freedom of the positionalrelationship between the projector and the circular cylinder;

FIG. 5 is a diagram illustrating the degree of freedom of the positionalrelationship between the projector and the circular cylinder;

FIG. 6 is a diagram illustrating an exemplary adjustment chart accordingto an embodiment;

FIG. 7 is a diagram illustrating an exemplary adjustment chart accordingto an embodiment;

FIG. 8 is a diagram illustrating an exemplary adjustment chart accordingto an embodiment;

FIG. 9 is a diagram illustrating an exemplary adjustment chart accordingto an embodiment;

FIG. 10 is a flowchart of an exemplary projection state adjustmentprocess according to an embodiment;

FIG. 11 is a flowchart of an exemplary first adjustment chart processaccording to an embodiment;

FIG. 12 is a flowchart of an exemplary adjustment process according toan embodiment;

FIG. 13 is a diagram of an exemplary projection state of an adjustmentchart onto the circular cylinder before the projection state adjustmentprocess;

FIG. 14 is a diagram of an exemplary projection state of an adjustmentchart onto the circular cylinder after the first adjustment chartprocess;

FIG. 15 is a flowchart of an exemplary second adjustment chart processaccording to an embodiment;

FIG. 16 is a diagram of an exemplary projection state of an adjustmentchart onto the circular cylinder after the second adjustment chartprocess;

FIG. 17 is a flowchart of an exemplary third adjustment chart processaccording to an embodiment;

FIG. 18 is a diagram of an exemplary projection state of an adjustmentchart onto the circular cylinder after the third adjustment chartprocess;

FIG. 19 is a flowchart of an exemplary fourth adjustment chart processaccording to an embodiment;

FIG. 20 is a diagram of an exemplary projection state of an adjustmentchart onto the circular cylinder after the fourth adjustment chartprocess;

FIGS. 21A to 21D are diagrams illustrating a first transformation and asecond transformation in the projection state adjustment processaccording to an embodiment;

FIG. 22 is a diagram illustrating projection of an image onto a circularcylinder using the projector according to an embodiment;

FIG. 23 is a diagram illustrating projection of an image onto a circularcylinder according to an exemplary modification of an embodiment;

FIG. 24 is a diagram illustrating projection of an image onto a curvedsurface according to an exemplary modification of an embodiment;

FIG. 25 is a diagram illustrating an adjustment chart according to anembodiment; and

FIG. 26 is a diagram illustrating an adjustment chart according to anembodiment.

DETAILED DESCRIPTION

An embodiment of the present invention will be described with referenceto the drawings. A projection apparatus according to the embodiment usesa digital light processing (DLP) (registered trademark) method using amicromirror display device.

FIG. 1 is a diagram of the schematic configuration of a projector 1 asthe projection apparatus according to the embodiment.

The projector 1 according to the embodiment can appropriately project animage with no distortion onto a circular cylinder.

Thus, the projector 1 performs geometric transformation on a projectedimage.

The projector 1 is configured to acquire parameters necessary forgeometric transformation from a user, as described later.

The projector 1 includes an input/output connector unit 11, aninput/output interface (I/F) 12, an image conversion unit 13, aprojection processing unit 14, a micromirror element 15, a light sourceunit 16, a mirror 18, a projection lens 20, a CPU 25, a main memory 26,a program memory 27, an operation unit 28, a posture sensor 29, an audioprocessing unit 30, a speaker 32, a projection adjustment unit 40, and asystem bus SB.

The input/output connector unit 11 is provided with a terminal such as apin jack (RCA) type video input terminal or a D-sub 15 type RGB inputterminal, for example, to which analog image signals are input.

The input image signals are input to the image conversion unit 13through the input/output I/F 12 and the system bus SB.

The input analog image signals in various standards are converted intodigital image signals at the input/output I/F 12.

It is noted that the input/output connector unit 11 may be configured toinclude an HDMI (registered trademark) terminal, for example, and toreceive digital image signals as well as analog image signals.

Moreover, the input/output connector unit 11 receives analog or digitalaudio signals.

The input audio signals are input to the audio processing unit 30through the input/output I/F 12 and the system bus SB.

Furthermore, the input/output connector unit 11 may be provided with anRS232C terminal or a USB terminal, for example.

The image conversion unit 13 is also called a scaler.

The image conversion unit 13 converts the input image data to adjustresolution, a grayscale level, and the like and generates image data ina predetermined format appropriate for projection.

The image conversion unit 13 transmits the converted image data to theprojection processing unit 14.

The image conversion unit 13 transmits, to the projection processingunit 14, image data on which symbols representing various operatingstates for an on-screen display (OSD) have been superimposed, asprocessed image data, when necessary.

Moreover, the image conversion unit 13 performs geometric transformationon a projected image to project, onto a projection target such as ascreen, an image in an appropriate shape in accordance with a projectionstate.

Specifically, in the embodiment, the image conversion unit 13 performsgeometric transformation to appropriately project an image onto acircular cylinder.

The light source unit 16 emits light of a plurality of colors includingthe primary colors of red (R), green (G), and blue (B).

The light source unit 16 is configured to sequentially emit theplurality of colors divided in time.

The light emitted from the light source unit 16 is totally reflected bythe mirror 18 and enters the micromirror element 15.

The micromirror element 15 includes a plurality of micromirrors arrangedin an array.

The micromirrors operate on/off at high speeds, and reflect the lightemitted from the light source unit 16 in a direction of the projectionlens 20, or divert the light in a direction away from the projectionlens 20.

A necessary number of the micromirrors for, for example, WXGA (WideeXtended Graphic Array) (1280 pixels wide×800 pixels high) is arrangedin the micromirror element 15.

With the reflection from the micromirrors, the micromirror element 15forms an image in, for example, the WXGA resolution.

In this manner, the micromirror element 15 functions as a spatialoptical modulator.

The projection processing unit 14 drives the micromirror element 15 todisplay an image represented by the image data transmitted from theimage conversion unit 13 in accordance with the image data.

In other words, the projection processing unit 14 operates on/off of themicromirrors of the micromirror element 15.

The projection processing unit 14 drives the micromirror element 15 intime division at high speeds.

The number of divisions of a unit time is obtained by multiplying aframe rate in accordance with a predetermined format [frames/second],the number of divided color components, and the number of displaygrayscale levels.

Moreover, the projection processing unit 14 also controls the operationof the light source unit 16 in synchronization with the operation of themicromirror element 15.

In other words, the projection processing unit 14 divides each frame intime, and controls the operation of the light source unit 16 tosequentially emit the light of all the color components in each frame.

The projection lens 20 adjusts the light guided from the micromirrorelement 15 to light to be projected onto a projection target (notillustrated) such as a screen or a circular cylinder.

Therefore, an optical image formed by the reflected light from themicromirror element 15 is projected and displayed on the projectiontarget such as a screen or a circular cylinder via the projection lens20.

The projection lens 20 includes a zoom mechanism and has a function ofchanging the size of an image to be projected.

Moreover, the projection lens 20 includes a focus adjustment mechanismfor adjusting the focus state of a projected image.

In this manner, the projection processing unit 14, the micromirrorelement 15, the light source unit 16, the projection lens 20, and thelike function as a projection unit 22 that projects an image.

The audio processing unit 30 includes a sound generator such as a PCMsound source.

The audio processing unit 30 drives the speaker 32 to amplify andrelease sounds based on analog audio data input from the input/outputconnector unit 11 or based on an analog signal obtained by convertingdigital audio data given upon projection operation.

Moreover, the audio processing unit 30 generates a beep sound and thelike when necessary.

The speaker 32 is a general speaker that emits the sound based on thesignal input from the audio processing unit 30.

The CPU 25 controls the operation of the image conversion unit 13, theprojection processing unit 14, the audio processing unit 30, and theprojection adjustment unit 40 described below.

The CPU 25 is connected to the main memory 26 and the program memory 27.

The main memory 26 includes, for example, an SRAM.

The main memory 26 functions as working memory of the CPU 25.

The program memory 27 includes an electrically rewritable nonvolatilememory.

The program memory 27 stores an operating program, various fixed-formatdata, and the like that are executed by the CPU 25.

Moreover, the CPU 25 is connected to the operation unit 28.

The operation unit 28 includes a key operation unit provided to a mainbody of the projector 1, and an infrared light receiving unit thatreceives infrared light from a remote control (not illustrated)dedicated to the projector 1.

The operation unit 28 includes an arrow key and an OK button.

The operation unit 28 outputs, to the CPU 25, a key operation signalbased on a key operated by a user with the key operation unit of themain body or the remote control.

The CPU 25 uses the program and data stored in the main memory 26 andthe program memory 27 to control the operation of the units of theprojector 1 in accordance with the user's instruction from the operationunit 28.

The posture sensor 29 includes a three-axis accelerometer, for example.

The accelerometer detects the angle of posture of the projector 1 in thegravity direction, that is, the angles of pitch and roll.

The posture sensor 29 outputs the detected result to the projectionadjustment unit 40.

However, the posture sensor 29 is not a necessary component, asdescribed later.

The projection adjustment unit 40 determines a transform function forimage geometric transformation used for appropriately projecting animage onto a circular cylinder, for example.

The projection adjustment unit 40 includes a chart generation unit 41, aparameter acquiring unit 42, a parameter storage unit 43, a transformfunction determination unit 44, a transform function storage unit 45,and a transform function reading unit 46.

The chart generation unit 41 generates a projection state adjustmentchart, described later.

The adjustment chart is generated by reading a grid pattern and markersor the like to display parameters to be presently adjusted, for example,which are recorded on the program memory 27.

The parameter acquiring unit 42 acquires 12 conversion parameters,described later, based on the input from the user, for example.

The parameter storage unit 43 stores the conversion parameters acquiredby the parameter acquiring unit 42.

The transform function determination unit 44 calculates a transformfunction for use in geometric transformation of an image based on theconversion parameters acquired by the parameter acquiring unit 42.

The transform function storage unit 45 stores the transform functioncalculated by the transform function determination unit 44.

The transform function reading unit 46 reads the transform functionstored on the transform function storage unit 45, and outputs thetransform function to the image conversion unit 13, for example.

The image conversion unit 13 performs the geometric transformation of animage based on the transform function.

The operation of the projector 1 according to the embodiment will bedescribed.

Let us consider the case where the projector 1 projects an image onto acurved surface formed of generatrices of a right circular cylinder.

First, the relationship among the projector 1, a circular cylinder 200,a projection area 100, and a target area 210 onto which an image isprojected, will be described with reference to FIG. 2.

Suppose that a range in which light emitted from the projection lens 20of the projector 1 is projected onto a projection target is referred toas the projection area 100.

On the surface of the circular cylinder 200, the area onto which animage is desired to be projected is referred to as the target area 210.

In the embodiment, the projector 1 operates to project an image onto thecircular cylinder 200 as if a sheet with a rectangular image depictedthereon is attached to the circular cylinder 200.

The target area 210 is the area corresponding to the sheet, onto whichan image is finally projected.

Here, a left side 212 and a right side 214 of the target area 210 areset parallel to a center axis 202 of the circular cylinder 200.

A top side 216 and a bottom side 218 of the target area 210 are disposedon a plane perpendicular to the center axis 202 of the circular cylinder200.

On the projection area 100, suppose that an area including an imagecorrected by geometric transformation is referred to as an image area101.

That is, the projector 1 according to the embodiment operates to matchthe image area 101 and the target area 210.

Here, the projector 1 performs geometric transformation to project adesired image onto the circular cylinder 200 as if a sheet with thisimage depicted thereon is attached to the circular cylinder 200.

With this geometric transformation, a desired image is included in theimage area 101, and the image area 101 matched with the target area 210.

First, the degree of freedom of the projection state will be describedwith reference to FIGS. 3 to 5.

As depicted in FIG. 3, a coordinate system is defined as follows, withthe position of the projection lens 20 of the projector 1 being theorigin point.

That is, the projection direction of the projector 1 is defined as az-axis.

The right direction of the projector 1 is defined as an x-axis, and theupper direction is defined as a y-axis on a plane perpendicular to thez-axis when the projector 1 is oriented in the z-axis direction.

FIG. 3 is a diagram of the positional relationship among the projector1, the circular cylinder 200, and the target area 210.

As described above, the left side 212 and the right side 214 of thetarget area 210 are parallel to each other, and the left side 212 andthe right side 214 are also parallel to the center axis 202 of thecircular cylinder 200.

Moreover, suppose that a plane passing through a top end 212-1 of theleft side 212 and perpendicular to the center axis 202 of the circularcylinder 200 is a first plane 221. The first plane 221 passes through atop end 214-1 of the right side 214.

Furthermore, in the intersection line of the circular cylinder 200 withthe first plane 221, a portion sandwiched between the left side 212 andthe right side 214 is matched with the top side 216 of the target area210.

Suppose that a plane passing through a lower end 212-2 of the left side212 and perpendicular to the center axis 202 of the circular cylinder200 is a second plane 222. The second plane 222 passes through a lowerend 214-2 of the right side 214.

In addition, in the intersection line of the circular cylinder 200 withthe second plane 222, a portion sandwiched between the left side 212 andthe right side 214 is matched with the bottom side 218 of the targetarea 210.

Suppose that the intersection point of the center axis 202 of thecircular cylinder 200 with the first plane 221 is a first center O1, andthe intersection point of the center axis 202 of the circular cylinder200 with the second plane 222 is a second center O2.

The degree of freedom of the circular cylinder 200 relative to theprojector 1 can be expressed by six degrees of freedom in total, i.e.,coordinates O1 (x1, y1, z1) of the first center O1 and coordinates O2(x2, y2, z2) of the second center O2.

It is noted that since the change in a radius R of the circular cylinderis the same as expansion or contraction of the entire coordinate systemincluding the projector 1 and the circular cylinder 200, the radius R ofthe circular cylinder is set to one, and is not included in the degreeof freedom.

FIG. 4 is a diagram of the first plane 221.

As depicted in FIG. 4, a rotation angle to the top end 214-1 of theright side 214 from a given reference line 226 is set to θ1, and arotation angle to the top end 212-1 of the left side 212 from thereference line 226 is set to θ2.

As described above, the left side 212 and the right side 214 on thecircular cylinder 200 can be expressed by two degrees of freedom.

Here, suppose that an angle expressing a portion onto which an imageexpressed by (θ2−θ1) is projected is referred to as a projection angleθ.

FIG. 5 is a diagram of a projection range on a plane where the zcoordinate of an image that the projector 1 projects is one.

The projection range is expressed in a rectangle, so that the projectionrange can be expressed by four degrees of freedom in total, i.e., upperleft coordinates D1 (x3, y3, 1) and lower right coordinates D2 (x4, y4,1), for example.

As described above, in the case where an image is projected onto thecircular cylinder 200 as if a sheet with a rectangular image depictedthereon is attached to the circular cylinder 200, and the right and leftsides of this image are adjusted to be parallel to the center axis 202of the circular cylinder 200, the degree of freedom of the projectionstate is 12 degrees in total.

In the projection state adjustment operation in which the projection ofan image onto the circular cylinder 200 is adjusted as described above,the projector 1 according to the embodiment provides the projectionstate adjustment operation in which the user can intuitively adjustprojection with a fewer number of manipulations and can accuratelyadjust the projection state.

As described above, since the degrees of freedom of projection onto thecircular cylinder are 12 degrees, it is necessary to acquire 12parameters in adjusting the projection state in order to accuratelyadjust the projection state.

Exemplary parameters for use in adjusting the projection state of theprojector 1 according to the embodiment and exemplary adjustment chartsfor use in adjusting the projection state will be described withreference to FIGS. 6 to 9.

Adjustment charts for use in adjusting the projection state according tothe embodiment are those as depicted in FIGS. 6 to 9.

All of these adjustment charts include the outer frame of the image area101 expressing an image on the projection area 100.

Moreover, for easy understanding, the adjustment charts include gridlines provided within the outer frame.

The grid lines are provided in such a way that intervals are providedequally on an image to be projected.

In the embodiment, adjustment markers, described later, included in theadjustment charts are adjusted so as to be matched with thecorresponding locations on the target area 210, which is the area ontowhich the image described with reference to FIG. 2 is projected, andthus the projection state is adjusted.

FIG. 6 is a diagram of a first adjustment chart 110.

The first adjustment chart 110 includes a first corner marker 112expressing the upper left corner of the image area 101, a second cornermarker 114 expressing the lower left corner of the image area 101, athird corner marker 116 expressing the lower right corner of the imagearea 101, and a fourth corner marker 118 expressing the upper rightcorner of the image area 101.

The projector 1 performs geometric transformation on the firstadjustment chart 110 in such a way that the first corner marker 112, thesecond corner marker 114, the third corner marker 116, and the fourthcorner marker 118 are each moved to the top, bottom, left, and right inresponse to user manipulations.

Since the first corner marker 112, the second corner marker 114, thethird corner marker 116, and the fourth corner marker 118 each have twodegrees of freedom, the first adjustment chart 110 has eight degrees offreedom in total.

That is, eight degrees of freedom out of the forgoing 12 degrees offreedom are defined using the first adjustment chart 110.

FIG. 7 is a diagram of a second adjustment chart 120.

The second adjustment chart 120 includes a median marker 122 expressinga line connecting the middle point of the projected image on the topside of the image area 101 to the middle point of the projected image onthe bottom side of the image area 101.

The projector 1 performs geometric transformation on the secondadjustment chart 120 in such a way that the median marker 122 is movedto the left and right in response to user manipulations.

Since the median marker 122 has one degree of freedom, the secondadjustment chart 120 has one degree of freedom.

That is, one degree of freedom out of the foregoing 12 degrees offreedom is defined using the second adjustment chart 120.

FIG. 8 is a diagram of a third adjustment chart 130.

The third adjustment chart 130 includes a top side marker 132 expressingthe middle point of the projected image on the top side of the imagearea 101 and a bottom side marker 134 expressing the middle point of theprojected image on the bottom side of the image area 101.

The projector 1 performs geometric transformation on the thirdadjustment chart 130 in such a way that the top side marker 132 and thebottom side marker 134 are moved vertically in response to usermanipulations.

Since the top side marker 132 and the bottom side marker 134 each haveone degree of freedom, the third adjustment chart 130 has two degrees offreedom in total.

That is, two degrees of freedom out of the foregoing 12 degrees offreedom are defined using the third adjustment chart 130.

FIG. 9 is a diagram of a fourth adjustment chart 140.

The fourth adjustment chart 140 includes a one-fourth line marker 142that is a line between the left side of the image area and the medianindicated by the foregoing median marker 122, and a three-fourths linemarker 144 that is a line between the right side of the image area andthe foregoing median.

The projector 1 performs geometric transformation on the fourthadjustment chart 140 in such a way that the one-fourth line marker 142and the three-fourths line marker 144 are moved to the left and right inresponse to user manipulations.

Here, the one-fourth line marker 142 and the three-fourths line marker144 are configured to move symmetrically (to change the width) with theforegoing median being the center axis.

That is, since the one-fourth line marker 142 and the three-fourths linemarker 144 have one degree of freedom, the fourth adjustment chart 140has one degree of freedom.

That is, one degree of freedom out of the foregoing 12 degrees offreedom is defined using the fourth adjustment chart 140.

As described above, in the embodiment, the first adjustment chart 110,the second adjustment chart 120, the third adjustment chart 130, and thefourth adjustment chart 140 define the 12 degrees of freedom.

As a result, the projector 1 can calculate a transform function forgeometric transformation necessary to accurately match the image area101 and the target area 210 using parameters input with the adjustmentcharts.

As described above, for example, the median marker 122 functions as afirst reference line.

For example, the one-fourth line marker 142 and the three-fourths linemarker 144 function as second reference lines.

Next, a projection state adjustment process in the projector 1 accordingto the embodiment will be described with reference to a flowchartdepicted in FIG. 10.

The projection state adjustment process is started by a user'sinstruction when the projector 1 is oriented toward the circularcylinder 200, for example.

In Step S101, the projection adjustment unit 40 performs a firstadjustment chart process of adjusting the positions of four corners ofthe image area.

The first adjustment chart process will be described with reference to aflowchart depicted in FIG. 11.

In Step S201, the projection adjustment unit 40 projects the firstadjustment chart 110.

That is, the projection adjustment unit 40 generates the firstadjustment chart 110, and causes the projection processing unit 14 toproject the first adjustment chart 110.

In Step S202, the projection adjustment unit 40 highlights the firstcorner marker 112 at the upper left on the first adjustment chart 110.

That is, the projection adjustment unit 40 generates the firstadjustment chart 110 on which the first corner marker 112 is highlightedmore than the other corner markers by changing the color or size of thefirst corner marker 112, for example, and outputs the first adjustmentchart 110 to the image conversion unit 13.

The image conversion unit 13 applies image conversion to the firstadjustment chart 110, and outputs the converted first adjustment chart110 to the projection processing unit 14.

The projection processing unit 14 projects the first adjustment chart110, which has undergone the image conversion and has been input fromthe image conversion unit 13.

In Step S203, the projection adjustment unit 40 performs an adjustmentprocess on the first corner marker 112.

The adjustment process will be described with reference to FIG. 12.

In Step S301, the projection adjustment unit 40 projects the adjustmentchart.

In the adjustment process on the first corner marker 112, the projectionadjustment unit 40 projects the first adjustment chart 110 on which thefirst corner marker 112 is highlighted.

In the projection, the user performs adjustment manipulations using thearrow key, for example.

For example, in the adjustment process on the first corner marker 112,the user inputs an instruction to move the first corner marker 112 tothe top, bottom, left, and right using the arrow key in such a way thatthe position of the first corner marker 112 is matched with the top end212-1 of the left side 212 of the target area 210.

In Step S302, the projection adjustment unit 40 determines whether theuser has performed adjustment manipulations.

When the projection adjustment unit 40 determines that adjustmentmanipulations have been made, the process goes to Step S303.

In Step S303, the projection adjustment unit 40 causes the imageconversion unit 13 to apply image conversion.

In the image conversion, the projection adjustment unit 40 determinesconversion parameters based on user adjustment manipulations, andcalculates a transform function for geometric transformation on theprojected image based on the conversion parameters.

The projection adjustment unit 40 outputs the calculated transformfunction to the image conversion unit 13.

The image conversion unit 13 performs arithmetic operations on geometrictransformation for the projected image based on the transform functionacquired from the projection adjustment unit 40.

After that, the process returns to Step S301.

For example, in the adjustment process on the first corner marker 112,the projection adjustment unit 40 determines conversion parameters formoving the projection position of the first corner marker 112 in thedirection corresponding to the pressed arrow key.

The projection adjustment unit 40 calculates a transform function todeform the first adjustment chart 110 based on the present transformfunction and the determined conversion parameters.

The user manipulates the arrow key in such a way that the position ofthe first corner marker 112 is matched with the top end 212-1 of theleft side 212 of the target area 210 while seeing the first adjustmentchart 110 projected onto the circular cylinder 200.

The projection adjustment unit 40 outputs the calculated transformfunction to the image conversion unit 13.

The image conversion unit 13 performs arithmetic operations on geometrictransformation for the first adjustment chart 110 based on the transformfunction acquired from the projection adjustment unit 40.

In Step S301, the first adjustment chart 110 subjected to geometrictransformation is projected.

In Step S302, when the projection adjustment unit 40 determines thatadjustment manipulations have not been made, the process goes to StepS304.

In Step S304, the projection adjustment unit 40 determines whether theuser has input OK indicating the completion of the adjustment process.

When the projection adjustment unit 40 determines that the user has notinput OK, the process returns to Step S301, and the present projectionis maintained.

On the other hand, when the projection adjustment unit 40 determinesthat the user has input OK, the process goes to Step S305.

For example, in the adjustment process on the first corner marker 112,when the position of the first corner marker 112 is matched with the topend 212-1 of the left side 212 of the target area 210, the user pressesthe OK button.

As described above, the conversion parameters on geometrictransformation for the adjustment chart are sequentially acquired inresponse to user adjustment manipulations until the user presses the OKbutton, and a transform function is calculated from the conversionparameters.

Moreover, geometric transformation is applied to the adjustment chartusing the calculated transform function, and the adjustment chartsubjected to the geometric transformation is projected.

In Step S305, the projection adjustment unit 40 stores the conversionparameters on the geometric transformation process in the previous StepS303 in the parameter storage unit 43, and records the transformfunction in the transform function storage unit 45.

After the recording, the adjustment process is ended, and the processreturns to the first adjustment chart process.

Referring again to FIG. 11, the description is continued on the firstadjustment chart process.

After the adjustment process in Step S203, the process goes to StepS204.

In Step S204, the projection adjustment unit 40 ends highlighting thefirst corner marker 112, and highlights the second corner marker 114 atthe lower left.

That is, the projection adjustment unit 40 generates the firstadjustment chart 110 on which the second corner marker 114 ishighlighted, and outputs the first adjustment chart 110 to theprojection processing unit 14 through the image conversion unit 13 forprojecting the first adjustment chart 110.

In Step S205, the projection adjustment unit 40 performs an adjustmentprocess on the second corner marker 114.

The adjustment process is similar to the case of the first corner marker112.

That is, the user manipulates the arrow key in such a way that thesecond corner marker 114 is matched with the lower end 212-2 of the leftside 212 of the target area 210.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the first adjustment chart 110 insuch a way that the projection position of the second corner marker 114is moved to the top, bottom, left, and right in response to pressing ofthe arrow key.

The image conversion unit 13 performs geometric transformation on thefirst adjustment chart 110 based on the calculated transform function.

When the position of the second corner marker 114 is matched with thelower end 212-2 of the left side 212 of the target area 210, the userpresses the OK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

In Step S206, the projection adjustment unit 40 ends highlighting thesecond corner marker 114, and highlights the third corner marker 116 atthe lower right.

In Step S207, the projection adjustment unit 40 performs an adjustmentprocess on the third corner marker 116.

The adjustment process is similar to the case of the first corner marker112.

That is, the user manipulates the arrow key in such a way that the thirdcorner marker 116 is matched with the lower end 214-2 of the right side214 of the target area 210.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the first adjustment chart 110 insuch a way that the projection position of the third corner marker 116is moved to the top, bottom, left, and right in response to pressing ofthe arrow key.

The image conversion unit 13 performs geometric transformation on thefirst adjustment chart 110 based on the calculated transform function.

When the position of the third corner marker 116 is matched with thelower end 214-2 of the right side 214 of the target area 210, the userpresses the OK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

In Step S208, the projection adjustment unit 40 ends highlighting thethird corner marker 116, and highlights the fourth corner marker 118 atthe upper right.

In Step S209, the projection adjustment unit 40 performs an adjustmentprocess on the fourth corner marker 118.

The adjustment process is similar to the case of the first corner marker112.

That is, the user manipulates the arrow key in such a way that thefourth corner marker 118 is matched with the top end 214-1 of the rightside 214 of the target area 210.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the first adjustment chart 110 insuch a way that the projection position of the fourth corner marker 118is moved to the top, bottom, left, and right in response to pressing ofthe arrow key.

The image conversion unit 13 performs geometric transformation on thefirst adjustment chart 110 based on the calculated transform function.

When the position of the fourth corner marker 118 is matched with thetop end 214-1 of the right side 214 of the target area 210, the userpresses the OK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

As described above, the first adjustment chart process is ended, and theprocess returns to the projection state adjustment process.

For example, suppose that the first adjustment chart 110 is firstprojected as depicted in FIG. 13.

Here, on the chart depicted in FIG. 13, for simplicity, the number ofgrids within the outer frame is half the number of grids on the chartdepicted in FIG. 6 vertically and horizontally.

Moreover, the markers are not displayed on the chart.

In FIG. 13, broken lines indicate the target area 210.

These also apply in FIGS. 14, 16, 18, and 20 below.

According to the first adjustment chart process described above, thefirst adjustment chart 110 projected as depicted in FIG. 13 is turnedinto the state in which the positions of four corners are matched withthe positions of four corners of the target area 210 as depicted in FIG.14.

Referring again to FIG. 10, the description is continued.

After the first adjustment chart process, in Step S102, the projectionadjustment unit 40 performs a second adjustment chart process.

An exemplary second adjustment chart process will be described withreference to FIG. 15.

Although the second adjustment chart process is different in theadjustment chart and the markers for use, the second adjustment chartprocess is basically similar to the first adjustment chart process.

In Step S401, the projection adjustment unit 40 projects the secondadjustment chart 120 including the median marker 122.

In Step S402, the projection adjustment unit 40 performs an adjustmentprocess on the median marker 122.

The user manipulates the left and right keys of the arrow key in such away that the median marker 122 is positioned in the middle between theleft side 212 and the right side 214 of the target area 210.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the second adjustment chart 120 insuch a way that the projection position of the median marker 122 ismoved to the left and right in response to pressing of the left andright keys.

The image conversion unit 13 performs geometric transformation on thesecond adjustment chart 120 based on the calculated transform function.

When the position of the median marker 122 is positioned in the middlebetween the left side 212 and the right side 214, the user presses theOK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

For example, according to the second adjustment chart process, theadjustment chart projected as depicted in FIG. 14 is turned as depictedin FIG. 16.

That is, the center in the lateral direction of the second adjustmentchart 120, which is the projected image, is matched with the center ofthe target area 210 in the lateral direction.

Referring again to FIG. 10, the description is continued.

After the second adjustment chart process, in Step S103, the projectionadjustment unit 40 performs a third adjustment chart process.

An exemplary third adjustment chart process will be described withreference to FIG. 17.

Although the third adjustment chart process is different in theadjustment chart and the markers for use, the third adjustment chartprocess is basically similar to the first adjustment chart process.

In Step S501, the projection adjustment unit 40 projects the thirdadjustment chart 130.

In Step S502, the projection adjustment unit 40 highlights the top sidemarker 132 on the third adjustment chart 130.

In Step S503, the projection adjustment unit 40 performs an adjustmentprocess on the top side marker 132.

The user manipulates the up and down keys of the arrow key in such a waythat the top side marker 132 is at the same height as the middle pointof the top side 216 of the target area 210, that is, the top side marker132 is matched with the middle point of the top side 216.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the third adjustment chart 130 insuch a way that the projection position of the top side marker 132 ismoved vertically in response to pressing of the up and down keys.

The image conversion unit 13 performs geometric transformation on thethird adjustment chart 130 based on the calculated transform function.

When the position of the top side marker 132 is at the same height asthe middle point of the top side 216 of the target area 210, the userpresses the OK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

In Step S504, the projection adjustment unit 40 highlights the bottomside marker 134 on the third adjustment chart 130.

In Step S505, the projection adjustment unit 40 performs an adjustmentprocess on the bottom side marker 134.

The user manipulates the up and down keys of the arrow key in such a waythat the bottom side marker 134 is at the same height as the bottom side218 of the target area 210, that is, the bottom side marker 134 ismatched with the middle point of the bottom side 218.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the third adjustment chart 130 insuch a way that the projection position of the bottom side marker 134 ismoved vertically in response to pressing of the up and down keys.

The image conversion unit 13 performs geometric transformation on thethird adjustment chart 130 based on the calculated transform function.

When the position of the bottom side marker 134 is at the same height asthe middle point of the bottom side 218 of the target area 210, the userpresses the OK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

As described above, the third adjustment chart process is ended, and theprocess returns to the projection state adjustment process.

For example, according to the third adjustment chart process, theadjustment chart projected as in FIG. 16 is turned as depicted in FIG.18.

It is noted that the order of performing the second adjustment chartprocess and the third adjustment chart process can be changed.

Moreover, the user may finely adjust the adjustment chart whilerepeating the second adjustment chart process and the third adjustmentchart process.

Adjustment using the second adjustment chart process and the thirdadjustment chart process is performed to match four corners of thetarget area 210 and four corners of the image area 101, which are on theouter frame of the adjustment chart.

Additionally, the middle point (the top side marker 132) of the top sideof the image area 101 is matched with the middle point of the top side216 of the target area 210, and the middle point (the bottom side marker134) of the bottom side of the image area 101 is matched with the middlepoint of the bottom side 218 of the target area 210.

It is noted that in some cases, the top side of the image area 101 isnot completely matched with the top side 216 of the target area 210 andthe bottom side of the image area 101 is not completely matched with thebottom side 218 of the target area 210 even though the second adjustmentchart process and the third adjustment chart process are performed.

Referring again to FIG. 10, the description is continued.

After the third adjustment chart process, in Step S104, the projectionadjustment unit 40 performs a fourth adjustment chart process.

An exemplary fourth adjustment chart process will be described withreference to FIG. 19.

Although the fourth adjustment chart process is different in theadjustment chart and the markers for use, the fourth adjustment chartprocess is basically similar to the first adjustment chart process.

In Step S601, the projection adjustment unit 40 projects the fourthadjustment chart 140 including the one-fourth line marker 142 and thethree-fourths line marker 144.

In Step S602, the projection adjustment unit 40 performs an adjustmentprocess on the one-fourth line marker 142 and the three-fourths linemarker 144.

The user manipulates the left and right keys of the arrow key in such away that the one-fourth line marker 142 is positioned in the middlebetween the left side 212 of the target area 210 and the median adjustedin the third adjustment chart process and the three-fourths line marker144 is positioned in the middle between the right side 214 of the targetarea 210 and the median.

The projection adjustment unit 40 calculates a transform function forgeometric transformation to deform the fourth adjustment chart 140 insuch a way that the projection positions of the one-fourth line marker142 and the three-fourths line marker 144 are moved to the left andright in response to pressing of the left and right keys.

The image conversion unit 13 performs geometric transformation on thefourth adjustment chart 140 based on the calculated transform function.

Here, the one-fourth line marker 142 and the three-fourths line marker144 are moved together symmetrically with respect to the median.

When the positions of the one-fourth line marker 142 and thethree-fourths line marker 144 are at desired positions, the user pressesthe OK button.

The conversion parameters and the transform function at this time arerecorded, and then the adjustment process is ended.

For example, according to the foregoing fourth adjustment chart process,the adjustment chart projected as in FIG. 18 is turned as depicted inFIG. 20.

That is, the image area 101, which is the outer frame of the fourthadjustment chart 140 and the projected image, is completely matched withthe outer frame of the target area 210, and images to be projected ateven intervals, for example, in the image area are projected at evenintervals.

That is, the images are projected as if a sheet with a rectangular imagedepicted thereon is attached to the circular cylinder.

Referring again to FIG. 10, the description is continued.

After the fourth adjustment chart process, in Step S105, the projectionadjustment unit 40 outputs a transform function finally calculated basedon 12 conversion parameters obtained as a result of the first to fourthadjustment chart processes.

The transform function is used for geometric transformation at the imageconversion unit 13 in image projection until the transform function iscanceled.

The transform function is stored in the transform function storage unit45 in association with the adjustment date and the setting name.

As described above, the projection state adjustment process is ended.

The transform function recorded in the transform function storage unit45 is read by the transform function reading unit 46 any time and outputto the image conversion unit 13 for use in image conversion at the imageconversion unit 13.

Therefore, for example, the positional relationship between theprojector 1 frequently used and the circular cylinder 200 is adjustedonce for the projection state. When the transform function is oncefound, the projection state adjustment process may not be performed forsecond time and later.

At this time, the transform function reading unit 46 reads the transformfunction stored in the transform function storage unit 45, and theprojector 1 can immediately project images correctly onto a desiredarea.

Next, geometric transformation performed in the adjustment process willbe described with reference to FIGS. 21A to 21D.

It can be considered that geometric transformation performed in theembodiment is divided into two image conversion processes.

As depicted in FIG. 21A, let us consider geometric transformation in thecase where the projector 1 projects an image onto the target area 210 onthe circular cylinder 200.

As indicated by a two-dot chain line in FIG. 21A, suppose that a planepassing through the right side and the left side of the target area 210is referred to as a cut plane 250.

Moreover, suppose that a plane perpendicular to the projection directionof the projector 1 is referred to as a projection plane 170.

Generally, as depicted in FIG. 21A, the cut plane 250 and the projectionplane 170 are not parallel to each other.

On the other hand, as depicted in FIG. 21B, in the case where the cutplane 250 and the projection plane 170 are parallel to each other,geometric transformation from the projection plane 170 to the targetarea 210 is relatively easily performed.

Therefore, in the embodiment, in the case where the cut plane 250 andthe projection plane 170 are not parallel to each other, let us consideran intermediate plane 180 parallel to the cut plane 250, as depicted inFIG. 21C.

Geometric transformation from the intermediate plane 180 to the targetarea 210 is a first transformation.

For example, suppose that four variables for the center (Ox, Oy, Oz) ofthe circular cylinder 200 and the projection angle θ expressing thewidth of the target area are variables expressing the circular cylinder200. The variables can be determined from the move parameter of themedian marker 122 in the lateral direction, the move parameter of thetop side marker 132 in the vertical direction, the move parameter of thebottom side marker 134 in the vertical direction, and a half value ofthe value of the projection angle θ expressing the width of the targetarea indicated by the one-fourth line marker 142 and the three-fourthsline marker 144.

Moreover, as depicted in FIG. 21D, conversion from the projection plane170 to the intermediate plane 180 is a second transformation.

This second transformation is rotation projection transformation from aplane to a plane generally known.

The transformation formula of the rotation projection transformation canbe determined from the coordinates of four corners of the image area 101determined using the first adjustment chart 110.

In the embodiment, geometric transformation from the projection plane170 to the target area 210 as depicted in FIG. 22 is performed by twotransformations, i.e., the first transformation and the secondtransformation described above.

Here, the parameters of the first transformation can be obtained by thesecond adjustment chart process using the second adjustment chart 120,the third adjustment chart process using the third adjustment chart 130,and the fourth adjustment chart process using the fourth adjustmentchart 140.

Furthermore, the parameters of the second transformation can be obtainedby the first adjustment chart process using the first adjustment chart110.

As described above, for example, the cut plane 250 corresponds to athird plane, and the first transformation corresponds to circularcylinder geometric transformation between the target area and the planeparallel to the third plane.

According to the projection state adjustment process of the embodiment,12 variables can be found by mathematically completely solving the 12variables based on inputs made by adjustment manipulations using thefirst to fourth adjustment charts, so that the transformation formula ofaccurate geometric transformation necessary for projection can bedetermined.

Moreover, 12 parameters input to solve the 12 variables include thepositions of four corners of the image area 101, the positions of thetop side and the bottom side in the vertical direction, the position ofthe median in the lateral direction, and the interval between theone-fourth line and the three-fourths line.

These parameters can be grasped by the user much more intuitively thanthe case where the user directly inputs the positional relationshipbetween the projector 1 and the circular cylinder 200, the projectionangle θ expressing the target area, and so on, for example.

Therefore, according to the embodiment, the user can intuitively performmanipulations in adjusting the projection state.

Moreover, the fact that the adjustment chart is updated in real time inresponse to the user input also facilitates manipulates by intuition.

Furthermore, since it is only necessary to input a minimum necessaryamount of parameters, i.e., the 12 parameters, the number ofmanipulations for adjustment is small for the user.

According to the embodiment, therefore, the user can intuitively,easily, and accurately adjust the projection state.

In addition, geometric transformation is determined in such a way thatthe transformation process is separated into the first transformationand the second transformation as in the embodiment, so that the amountof arithmetic operations is reduced.

This is effective for high-speed processing. In the embodiment, thecombination of the first adjustment chart 110 corresponding to the firsttransformation and the second adjustment chart 120, the third adjustmentchart 130, and the fourth adjustment chart 140 corresponding to thesecond transformation is used to easily separate geometrictransformation into the first transformation and the secondtransformation.

It is noted that in the embodiment, for example, the first to fourthadjustment chart processes are performed sequentially. However, thefirst to fourth adjustment chart processes may be appropriately returnedor skipped depending on the user's instruction.

Moreover, the order of procedures in each process, such as the firstadjustment chart process, can be similarly changed.

In the embodiment, the description has been made in which the userinputs all of unknown 12 parameters.

However, the projection adjustment unit 40 can acquire values related toa part of parameters even though the user does not always input theseparameters.

For example, the projection adjustment unit 40 can acquire the angle ofview of the projection lens 20 from a sensor provided on the projectionlens 20 or from a control unit controlling the projection lens 20.

Furthermore, the projection adjustment unit 40 can acquire the postureof the projector 1, for example, from the foregoing posture sensor 29.

The projection adjustment unit 40 may acquire the diameter of thecircular cylinder 200 input to the operation unit 28 by the user oracquire the positional relationship between the optical axis of theprojector 1 and the circular cylinder 200.

Even though some of the 12 parameters are not input, all the 12 degreesof freedom are calculated and an accurate transform function can beacquired, as long as the values of the parameters are acquired.

That is, user manipulations necessary for adjustment can be reduced.

As described above, for example, the portion where the angle of view ofthe projection lens 20 is acquired and the posture sensor 29 function asa condition acquiring unit to acquire the positional relationshipbetween the projection unit and the target area, but the portion and theposture sensor 29 are not necessarily included in the configuration.

For example, arithmetic operations for bilaterally symmetricalparameters can be reduced in the conversion parameters acquired usingthe first to fourth adjustment charts, as long as it is apparent thatthe projector 1 is disposed directly opposite to the circular cylinder200.

In this case, for example, the corner markers on the first adjustmentchart may be moved in bilateral symmetry, and adjustment to be made bythe third adjustment chart becomes unnecessary.

Moreover, adjustment to be made by the fourth adjustment chart becomesunnecessary as long as the projection angle θ is apparent.

In the embodiment, an example has been described in which an image isprojected onto the right circular cylinder. However, the case where animage is projected onto an oblique circular cylinder is also similar tothe description above, as long as the left and right sides of the targetarea are parallel to the axis of the oblique circular cylinder.

Furthermore, in the embodiment, the conditions are given that the rightand left sides of the target area 210 are parallel to the axis of thecircular cylinder 200. However, for example, as depicted in FIG. 23, thetarget area 210 may be rotated with respect to the axis of the circularcylinder.

In this case, there are 13 conversion parameters.

In this case, for example, a chart can be used, as a fifth adjustmentchart, to adjust this rotation angle.

Although the number of conversion parameters is increased, a variety ofprojection is made possible.

In addition, in the embodiment, an example has been described in whichan image is projected onto the protruding curved surface of a circularcylinder.

However, as depicted in FIG. 24, also the case where an image isprojected onto a recessed curved surface 300 forming a part of acircumferential surface can be operated similarly to the foregoingembodiment, not limited to the protruding curved surface.

In the projection, it is not necessary to change the settings of theprojector 1.

That is, the user can adjust the projection state by completely the samemanipulates without regard to whether the cylinder is circular orrecessed.

Moreover, in the embodiment, an example has been shown in which an imageis projected onto a curved surface. However, the projection adjustmentunit 40 can also be used for adjusting the projection state in the casewhere an image is projected onto a plane (which corresponds to acircular cylinder surface with an infinite radius).

In this case, the first adjustment chart process alone may be performedin which the first adjustment chart 110 is used to match four corners ofthe image area and four corners of the target area, and it is notnecessary to perform the second to fourth adjustment chart processes.

That is, the second transformation alone may be performed between theforegoing first transformation and second transformation.

In adjustment using the adjustment chart, a position guide mark may bedisplayed near the center of the adjustment chart in such a way that theuser can clearly recognize which point the user is currently adjustingor the user can recognize the direction of a peripheral part of theadjustment chart even in the case where the peripheral part is out ofthe circular cylinder and not projected.

For example, as depicted in FIG. 25, when the first corner marker 112 onthe first adjustment chart 110 is being adjusted, the first adjustmentchart 110 may include the position guide mark 113 near the center of thefirst adjustment chart 110.

Similarly, for example, as depicted in FIG. 26, when the top side marker132 on the third adjustment chart 130 is being adjusted, the thirdadjustment chart 130 may include a position guide mark 133 near thecenter of the third adjustment chart 130.

Moreover, intervals to update the values of the parameters by usermanipulations may be linearly changed in response to the number ofpressing the arrow key or the time to press the arrow key, for example,or may be changed in a different way.

For example, intervals can be changed for a shorter time or a longertime according to parameter values or user's instructions.

The present invention is not limited to the embodiments as they are, andcan be embodied in the implementation stage by deforming the componentswithin a range that does not depart from its spirit.

Moreover, various embodiments of the invention can be formed by anappropriate combination of a plurality of the components disclosed inthe embodiments.

For example, even if some components are deleted from all the componentsillustrated in the embodiments, if the problem stated in the relatedart, the problem being attempted to be solved by the embodiments of theinvention, can be solved and, if the effects of the embodiments of theinvention can be obtained, the configuration where the components havebeen deleted can be extracted as an embodiment of the invention.

Furthermore, the components over the different embodiments may becombined as appropriate.

What is claimed is:
 1. A projection state adjustment method forprojecting an image of an image area to be projected from a projectionunit onto a target area on a curved surface formed of generatrices of acircular cylinder, the method comprising: determining a transformfunction for use in geometric transformation based on a positionalrelationship between the projection unit and the curved surface; andapplying geometric transformation to a projected image using thetransform function, wherein in the determining, a first manipulation bya user is acquired to adjust positions of four corners of the image areaand a user manipulation other than the first manipulation is acquired.2. The projection state adjustment method according to claim 1, whereinthe first manipulation includes a manipulation to match the four cornersof the image area and four corners of the target area.
 3. The projectionstate adjustment method according to claim 1, wherein in the determiningas a user manipulation other than the first manipulation, a secondmanipulation by the user is acquired to adjust a position of a firstreference line connecting a first middle point that is a middle point ofa top side of the image area to a second middle point that is a middlepoint of a bottom side of the image area.
 4. The projection stateadjustment method according to claim 3, wherein the target area is anarea surrounded by: a first line and a second line which are parallel toan axis of the circular cylinder; a third line that is an intersectionline of a first plane perpendicular to the axis and the curved surface;and a fourth line that is an intersection line of a second planeparallel to the first plane and the curved surface, and the secondmanipulation includes a manipulation to, when a position in an axialdirection provided perpendicularly to the first line is referred to as ahorizontal position, match a horizontal position of the first referenceline and horizontal positions of a middle point of the third line and amiddle point of the fourth line by changing a horizontal position of thefirst reference line.
 5. The projection state adjustment methodaccording to claim 1, wherein in the determining step, as a usermanipulation other than the first manipulation, a third manipulation bythe user is acquired to adjust a position of a first middle point thatis a middle point of a top side of the image area to a directionorthogonal to the top side, and/or adjust a position of a second middlepoint that is a middle point of a bottom side of the image area to adirection orthogonal to the bottom side.
 6. The projection stateadjustment method according to claim 5, wherein the target area is anarea surrounded by: a first line and a second line which are parallel toan axis of the circular cylinder; a third line that is an intersectionline of a first plane perpendicular to the axis and the curved surface;and a fourth line that is an intersection line of a second planeparallel to the first plane and the curved surface, and the thirdmanipulation includes a manipulation to, when a position in an axialdirection provided parallel to the first line is referred to as height,match a height of the first middle point and a height of the middlepoint of the third line by changing the height of the first middlepoint, and/or match a height of the second middle point and a height ofthe middle point of the fourth line by changing the height of the secondmiddle point.
 7. The projection state adjustment method according toclaim 1, wherein in the determining, as a user manipulation other thanthe first manipulation, a fourth manipulation by the user is acquiredto, when a line connecting a first middle point that is a middle pointof a top side of the image area to a second middle point that is amiddle point of a bottom side of the image area is referred to as afirst reference line, adjust a position of a second reference lineprovided between a left side of the image area and the first referenceline, or between a right side of the image area and the first referenceline.
 8. The projection state adjustment method according to claim 7,wherein the target area is an area surrounded by: a first line and asecond line which are parallel to an axis of the circular cylinder; athird line that is an intersection line of a first plane perpendicularto the axis and the curved surface; and a fourth line that is anintersection line of a second plane parallel to the first plane and thecurved surface, the second reference line is a one-fourth lineconnecting a middle point between the upper left corner and the firstmiddle point to a middle point between the lower left corner and thesecond middle point and a three-fourths line connecting a middle pointbetween the upper right corner and the first middle point to a middlepoint between the lower right corner and the second middle point, andthe fourth manipulation includes a manipulation to match the third linewith the top side and the fourth line with the bottom side by moving theone-fourth line and the three-fourths line to a direction perpendicularto the first line.
 9. The projection state adjustment method accordingto claim 1, wherein the determining includes generating an adjustmentchart, and in the determining, a user manipulation related to theadjustment chart generated in the chart generating is acquired.
 10. Theprojection state adjustment method according to claim 1, wherein thedetermining includes determining twelve parameters for projecting theimage area onto the target area.
 11. The projection state adjustmentmethod according to claim 1, wherein the geometric transformationincludes: rotation projection transformation between a plane and aplane; and circular cylinder geometric transformation between a planeand the target area.
 12. A projection state adjustment method forprojecting an image of an image area to be projected from a projectionunit onto a target area on a curved surface formed of generatrices of acircular cylinder, the method comprising: determining a transformfunction for use in geometric transformation based on a positionalrelationship between the projection unit and the curved surface; andapplying geometric transformation to a projected image using thetransform function, wherein in the determining, a user manipulation isacquired to, when a line connecting a first middle point that is amiddle point of a top side of the image area to a second middle pointthat is a middle point of a bottom side of the image area is referred toas a first reference line, adjust a position of a second reference lineprovided between a left side of the image area and the first referenceline, or between a right side of the image area and the first referenceline.
 13. A projection state adjustment method for projecting an imageof an image area to be projected from a projection unit onto a targetarea on a curved surface formed of generatrices of a circular cylinder,the method comprising determining a transform function for use ingeometric transformation based on a positional relationship between theprojection unit and the curved surface; and applying geometrictransformation to a projected image using the transform function,wherein in the determining, a first manipulation by the user is acquiredto match four corners of the image area and four corners of the targetarea, and subsequently to the first manipulation, a second manipulationby the user is acquired to adjust a position of a first reference lineconnecting a first middle point that is a middle point of a top side ofthe image area to a second middle point that is a middle point of abottom side of the image area.
 14. The projection state adjustmentmethod according to claim 13, wherein in the determining, subsequentlyto the second manipulation, a third manipulation by the user is acquiredto adjust a position of a first middle point that is a middle point of atop side of the image area to a direction orthogonal to the top side,and/or adjust a position of a second middle point that is a middle pointof a bottom side of the image area to a direction orthogonal to thebottom side.
 15. The projection state adjustment method according toclaim 14, wherein in the determining, subsequently to the thirdmanipulation, a fourth manipulation by the user is acquired to, when aline connecting a first middle point that is a middle point of a topside of the image area to a second middle point that is a middle pointof a bottom side of the image area is referred to as a first referenceline, adjust a position of a second reference line provided between aleft side of the image area and the first reference line, or between aright side of the image area and the first reference line.